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Pushing the limits of aluminium recycling

Updated: Nov 10, 2021

«Organic in greens, plastic in pinks, paper in blues». The colour coding is the first you will learn about the recycling system in Norway.

PoS – Interview with Alicia Vallejo-Olivares, PhD candidate at NTNU

by Fjorida Llaha


«Organic in greens, plastic in pinks, paper in blues». The colour coding is the first you will learn about the recycling system in Norway.

But this is not all. Then you have to separate the glass, metal, electronics, and pay close attention to plastics bottles and beverage cans because they have a pant value that you pay and get it back only when you return them in the reverse vending machines at the stores. Yes, the Norwegian recycling system is one of the most efficient worldwide. Still, it must continue to improve as the amount and complexity of waste keep growing, endangering the environment and human health.


«Sustainable Materials–with both eyes open» is a book that broadly explains the main strategies for sustainable materials, particularly steel and aluminium, which alone account for 30 per cent of global emissions. This book was a starting inspiration for Alicia in the world of sustainability.

Alicia Vallejo-Olivares is a PhD-candidate at the Department of Materials Science and Engineering at the Norwegian University of Science and Technology (NTNU), working in the Alpakka project.


So, what is the goal of the Alpakka project?


To recycle and bring back into the market all the aluminium food packaging consumed in Norway. In other words: the circularity of aluminium food packaging.

We work to improve the recycling process, the collection and sorting schemes, and the product design.

Even with the dedicated collection schemes for packaging in Norway, thousands of tonnes of aluminium end up in the incineration plants every year. Substituting primary aluminium (non-recycled) with recycled aluminium saves huge amounts of energy, greenhouse emissions and waste, so we want to make sure that we recover as much as possible.


As part of my PhD, I study how the thickness and coatings in products influence the recyclability of packaging materials and whether the process could be improved by pre-treatments such as compaction or heating up the scrap before re-melting it.


You said still thousands of tonnes of wasted aluminium end up in incineration plants. Why do you think this is happening?


Although most people have good recycling intentions, many still encounter doubts about what to recycle and how. We need better communication on the labels and in general about how the recycling system works. For example, making sure that the metal waste is clean and dry helps the handling and re-melting processes. Plus, the aluminium in some products is not yet recycled, for example, the thin layer in the tetra pack or the crisps bags, because it is challenging to separate the layers without oxidizing the aluminium.


Colour coding and symbols for waste collection in Norway (source https://sortere.no/avfallssymboler#toggle-id-14)

What got you interested in the Alpakka project?


After graduating, I worked for a year in a software company in the UK, developing resources for teaching sustainability to engineering students. During this period, I was inspired by a waste management event at the British Antarctic Survey, and by working with an eminent professor, Mike Ashby. Then, I decided to continue my career with a PhD and contribute to a more sustainable aluminium industry. When I found the Alpakka project, I was impressed by the collaboration between the food industry, aluminium producers and recyclers, waste collectors, and research institutions. Opening these communication channels between the stakeholders and research institutions is crucial for a circular economy.


How is working at your lab?


My main experiments are compacting and then re-melting aluminium in a small furnace to measure how much metal I recover and its quality. I enjoy alternating the office work with the practical work; time does fly sometimes. But we always need to keep a cold head and be aware of the risks. I want to send a big thank you to the engineers who keep the laboratories running and teach us how to work safely.




“Keep calm, and keep stirring the aluminium pot”


What actions would you suggest to the people or the Norwegian government to improve aluminium recycling?


Get well informed on how aluminium is collected in your area because it can vary from place to place. In Trondheim, we need to rinse and dispose of the aluminium packaging, aluminium foil, tea lights (candles), etc. in the container for glass and metal and return the aluminium cans (pant) to the store. As consumers, we should also choose recyclable materials or recycled sources when possible. The government can push towards sustainability through regulations or tax incentives for industry and by supporting more educational and research projects.


How was your PhD journey affected by the Covid-19 crisis?


Like in many universities around the world, we switched most activities online, but overall, we didn’t have it too bad in Trondheim. I could still go to the lab, and there was never a strict «lockdown» in the city. I can see how digital courses and conferences have certain advantages: saving time, money, and emissions from travelling. But still, the face-to-face discussions and networking events are critical for a PhD, and I look forward to attending some on-site events in few months (and travelling!).

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